Life cycle assessment (LCA) and environmentally extended input–output analyses (EEIOA) are two techniques commonly used to assess environmental impacts of an activity/product. Their strengths and weaknesses are complementary, and they are thus regularly combined to obtain hybrid LCAs. A number of approaches in hybrid LCA exist, which leads to different results. One of the differences is the method used to ensure that mixed LCA and EEIOA data do not overlap, which is referred to as correction for double counting. This aspect of hybrid LCA is often ignored in reports of hybrid assessments and no comprehensive study has been carried out on it. This article strives to list, compare, and analyze the different existing methods for the correction of double counting. We first harmonize the definitions of the existing correction methods and express them in a common notation, before introducing a streamlined variant. We then compare their respective assumptions and limitations. We discuss the loss of specific information regarding the studied activity/product and the loss of coherent financial representation caused by some of the correction methods. This analysis clarifies which techniques are most applicable to different tasks, from hybridizing individual LCA processes to integrating complete databases. We finally conclude by giving recommendations for future hybrid analyses.

中文翻译：

---

揭开纠正混合生命周期评估中重复计数事件的面纱

生命周期评估（LCA）和环境扩展的投入产出分析（EEIOA）是两种通常用于评估活动/产品对环境的影响的技术。它们的优缺点是相辅相成的，因此有规律地将它们组合在一起以获得混合LCA。混合LCA中存在许多方法，导致不同的结果。区别之一是用于确保混合的LCA和EEIOA数据不重叠的方法，称为重复计数校正。混合LCA的这一方面在混合评估报告中经常被忽略，并且尚未对此进行全面研究。本文力求列出，比较和分析重复计数校正的各种现有方法。在引入简化的变体之前，我们首先统一现有校正方法的定义，并以通用符号表示它们。然后，我们比较它们各自的假设和局限性。我们讨论了有关所研究活动/产品的特定信息的丢失，以及由于某些更正方法而导致的财务连贯性的损失。该分析阐明了从混合单个LCA流程到集成完整数据库，哪些技术最适用于不同任务。最后，我们为将来的混合分析提供了建议。我们讨论了有关所研究活动/产品的特定信息的丢失，以及由于某些更正方法而导致的财务连贯性的损失。该分析阐明了从混合单个LCA流程到集成完整数据库，哪些技术最适用于不同任务。最后，我们为将来的混合分析提供了建议。我们讨论了有关所研究活动/产品的特定信息的丢失，以及由于某些更正方法而导致的财务连贯性的损失。该分析阐明了从混合单个LCA流程到集成完整数据库，哪些技术最适用于不同任务。最后，我们为将来的混合分析提供了建议。